Each logical unit is mapped to 0.1 millimeter. Positive x is to the right;
positive y is down.

PDTS_HIMETRIC

Each logical unit is mapped to 0.01 millimeter. Positive x is to the right;
positive y is down.

PDTS_HIENGLISH

Each logical unit is mapped to 0.001 inch. Positive x is to the right;
positive y is down. This is equivalent to PDTS_STANDARDSCALE.

PDTS_DISPLAY

This parameter scales the data, using DPtoTP. The pen data memory block is left in display coordinates.

Return Value

Returns TRUE if successful, or FALSE if hpndt is in a compressed state or if the data is not already in one of the metric
modes such as PDTS_ARBITRARY.

Comments

The MetricScalePenData function converts pen coordinates between metric and English standard
measurements. Metric units are 0.1 and 0.01 millimeter; English standard units are
0.001 inch. These scaling metrics form the same mapping mode set in the Windows
function SetMapMode.

MetricScalePenData allows an application to transform pen data to the mapping mode set for a
device context. This ensures that ink rendered in the device context appears in
the proper scale.

Note the following caveats about MetricScalePenData:

Because of rounding errors, scaling is not precisely reversible between
mapping modes. Rounding errors can also adversely affect recognition accuracy if the
data is later given to a recognizer. The problem arises when transforming the
standard ink scale of HIENGLISH to a scale of lower resolution, a transformation
that loses some of the original data. The lost data cannot be recovered, even
if the coordinates are converted back into HIENGLISH.

The scaling is not perfect and results in numerous "off-by-one" discrepancies,
visible when displaying the scaled data.

Strictly speaking, the PDTS_DISPLAY scaling type is not a metric scale. To use
it, the current scale of the data must be in PDTS_STANDARDSCALE units.

The effect of this call is similar to that of using the TPtoDP function on the array of points. A recognizer may not accurately recognize
the resulting data. As with the other scales, the PDTS_DISPLAY is set in the wPndts member of the pen data header. If data is in PDTS_DISPLAY scale, MetricScalePenData cannot be called to scale it back to the other metric scales. No overflow
checks are made. Because of rounding errors, scaling conversion is not perfectly
reversible. Recognizers must recognize points that have been scaled to
PDTS_STANDARDSCALE (equivalent to PDTS_HIENGLISH).